Influence of surroundings of early-tomato greenhouses on crop colonization by predatory mirid bugs

Abstract

Biological control of crop pests is considered a promising conservation strategy in horticultural crops. In the Mediterranean region, crop colonization by native predatory mirid bugs is frequent but highly varied between crop production sites, which helps to increase the populations of pests’ natural enemies. This study seeks to determine the factors related to landscape heterogeneity around primary tomato crops which could favour colonization by polyphagous predators and improve conservation biological control (CBC). We describe the diversity and abundance of plant species of the vegetation surrounding 12 greenhouses located in the Maresme region. The vegetable host species of the predatory mirid bugs were determined and the two cryptic species of the main predator Macrolophus spp. were separated. Additionally, the abundance of mirid bugs surrounding greenhouses was determined and linked to crop colonization. Up to 14 plant-species hosts of predatory mirid bugs of 8 different plant families, most of them breeders, were found. The most abundant mirid bugs were Macrolophus spp, found on 12 different plant species, followed by Dicyphus tamaninii. It was confirmed that the mirid species found on the vegetation under study was Macrolophus pygmaeus, which is the one that colonizes tomato crops. The greatest abundance of M. pygmaeus was found on the ornamental plant Calendula officinalis but Nesidiocoris tenuis, which could generate a competition problem or crop damage, was also found. The results suggest that a heterogeneous landscape rich in host plants for predatory mirid bugs generates a greater abundance of such insects that can colonize the greenhouse tomato crops in the Mediterranean region.

Keywords: Macrolophus pygmaeus, conservation biological control, greenhouse, tomato, Calendula officinalis.